Re: Add the command \offset to LilyPond (issue 8647044)

[david . nalesnik]

On 2013/10/20 16:15:56, dak wrote:
> On 2013/10/20 15:51:57, david.nalesnik wrote:
> >
https://codereview.appspot.com/8647044/diff/48001/scm/music-functions.scm
> > File scm/music-functions.scm (right):
> >
> >

https://codereview.appspot.com/8647044/diff/48001/scm/music-functions.scm#newcode2118
> > scm/music-functions.scm:2118: (let* ((immutable
(ly:grob-basic-properties
> grob))
> > I just noticed something unfortunate while attempting to write
documentation
> for
> > \offset.  Basically, `property' needs to be specified using the
older notation
> > -- i.e., with #' prefixed.

> I suggest looking at the code in issue 3625.  That "sloppy" approach
let's you
> concatenate the material first (requiring the symbol? check, though)
and then
> pull the whole thing through the property path checker.  In this case,
it would
> appear that you want to call it with #:min 3 #:max 3 #:default 'Bottom
as
> anything but a toplevel property would be a cause for problems.

> And you should be able to get at your property using (third p) or so.
A similar
> recipe should be good for tweaks, just using a different #:start value
for the
> check.

OK, that makes sense.  I've rewritten offset according to these
guidelines.  A side benefit
is that it was no trouble to allow directed tweaks, so the following is
possible:

{
  <c'' e'' \offset AccidentalPlacement.right-padding #2 ges''!>4
  <c'' e'' \offset X-offset #-2 ges''!>4
}

Tweaks following tweaks work, too:

{
  <c'' e''
  \offset AccidentalPlacement.right-padding #2
  \offset X-offset #-2 ges''!>4
}

Here's what I come up for offset:

offset =
#(define-music-function (parser location property offsets item)
  (symbol-list-or-symbol? scheme? symbol-list-or-music?)
  (_i "Offset the default value of @var{property} of @var{item} by
@var{offsets}.  If @var{item} is a string, the result is
@code{\\override} for the specified grob type.  If @var{item} is
a music expression, the result is the same music expression with an
appropriate tweak applied.")
  (if (ly:music? item)
      ; In case of a tweak, our grob property path
      ; is Grob.property.
      (let ((prop-path (check-grob-path
                          (if (symbol? property)
                              (list property)
                              property)
                          parser location
                          #:start 1 #:default #t #:min 2 #:max 2)))
        (if prop-path
            ; If the head of the grob property path is a
            ; symbol--i.e., a grob name--produce a directed
            ; tweak.  Otherwise, create an ordinary tweak.
            (if (symbol? (car prop-path))
                #{
                  \tweak #prop-path
                         #(offsetter (second prop-path) offsets) #item
                #}
                #{
                  \tweak #(second prop-path)
                         #(offsetter (second prop-path) offsets) #item
                #})
            (make-music 'Music)))
      ; In case of an override, our grob property path
      ; is Context.Grob.property
      (let ((prop-path (check-grob-path
                          (append item
                                  (if (symbol? property)
                                      (list property)
                                      property))
                          parser location
                          #:default 'Bottom #:min 3 #:max 3)))
        (if prop-path
            #{
              \override #prop-path =
                #(offsetter (third prop-path) offsets)
            #}
            (make-music 'Music)))))

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Thank you very much for your help!



https://codereview.appspot.com/8647044/